Pain: opioids, acetaminophen… new forms to improve their use
Acute pain: the choice of quick relief
Back pain, migraine, joint pain, inflammatory pain, post-surgical pain… 92% of people declare suffering from short (acute pain) or persistent (chronic pain: more than 3 months and resistant to treatment) pain each year. Pain is part of French daily lives and is the first cause of medical consultation.
The World Health Organization has classified drugs for pain relief into three distinct categories.
– Tier 1 analgesics are recommended to treat mild to moderate pain. The main tier 1 medications are acetaminophen, aspirin, NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen for example.
– Tier 2 analgesics, prescribed to relieve moderate to severe pain — i.e. pain that cannot be treated by Tier 1 medications — are weak opioid pain medications such as tramadol or codeine.
– Tier 3 analgesics are recommended for severe pain or pain resistant to Tier 2 medication. These are strong opioid pain medications: morphine and its derivatives. These drugs work similarly to Tier 2 opioids but are more powerful, with greater side effects and may cause addiction problems.
The galenic form is chosen according to the administration mode (oral, rectal, intravenous…) and influences the speed of action of the drug.
Standard release treatments are used to treat acute pain. Most of them are available as capsules, tablets, effervescent tablets, orodispersible or sublingual tablets.
Effervescent tablets dissolve quickly in water and release the active substance in the stomach in under 15 minutes, with an effect in 30 to 45 minutes.
Orodispersible tablets dissolve under the tongue in 10 to 45 seconds. They are ideal for people who have difficulty swallowing (elderly patients and/or patients with neurocognitive disorders).
Acetaminophen is also available in liquid stick-packs. This innovative galenic form is particularly suitable for young children: its pre-measured dose ensures practicality and proper usage.
These same drugs may also be formulated as injectable forms for intravenous administration.
Chronic pain and sustained-release forms… to reduce side effects and the number of daily doses
Long-acting forms of painkillers are an excellent alternative for chronic pain. These extended-release (ER) medications may be oral or injectable and provide prolonged and stable systemic levels of the active ingredient. Dissolution and absorption occur in the intestine, releasing the medication slowly over an extended period.
These forms avoid gastric irritation or degradation of fragile active ingredients in acidic stomach pH. They are mostly gastro-resistant.
Their main advantage is reducing the number of daily doses, particularly in chronic pain.
Morphine and its derivatives in ER forms reduce both dosing frequency and side effects.
Similarly, the introduction of tramadol hydrochloride ER has significantly improved pain management by extending the duration of action while offering excellent stability and tolerability. This form is increasingly used in pediatrics.
These ER forms must never be crushed to maintain their prolonged effect. Pharmaceutical counseling is required when dispensing!
Patches and drugs in transdermal form
Transdermal patches provide another route and effect profile: introduced in the 1990s, these systems deliver the active ingredient through the skin into the bloodstream, bypassing the digestive and hepatic system. This avoids certain side effects seen with NSAIDs, for example.
Most pain patches contain a morphine derivative such as fentanyl, which can also be injected or administered via nasal or oral transmucosal routes.
Reservoir patches contain a pouch where the active ingredient is in liquid or gel form, being released through a semi-permeable membrane.
In matrix patches, the active ingredient is dissolved or dispersed within the matrix.
New generations of patches use technologies such as low electric current (iontophoresis), electroporation, ultrasound, and microneedles.
More recently, transdermal patches with high‑activity cannabinoid extracts (CBD) have been developed. As cannabinoids are absorbed through the skin, they provide sustained analgesic and anti-inflammatory effects.
They are particularly beneficial for managing chronic pain such as fibromyalgia and neuropathic pain in diabetic patients.
However, France’s ANSM warns patients and healthcare professionals about risks of misuse, forgetting to remove patches, and overdose linked to transdermal devices.
Sources :
https://www.hauts-de-france.ars.sante.fr/prise-en-charge-de-la-douleur-chronique-1
https://www.atelierantalgie.com/blog/2017/12/05/douleurs-quelles-formes-galeniques-privilegier/